Raping a planet involves considerable expense. Enormous blasters and slicers and sluicers and refiners are required to reduce a world back almost to a state of primal chaos, and then to extract from it its essential (i.e., commercially viable) ingredients. The history books may tell you of strip-mining on the mother planet, back in ancient times. Well, the crude processes employed then were similar in emphasis and results, but the operations were considerably smaller in size.